Photocatalytic Concrete Research Articles

Study of the influence of nano-TiO2 on the properties of Portland cement concrete for application on road surfaces

This paper reports the results obtained in a study on the effect of the addition of TiO2 nanoparticles on the mechanical properties and microstructural characteristics of photocatalytic concretes. Concretes were produced with three types of TiO2: anatase I (10–30 nm), anatase II (50–80 nm) and rutile (10 × 40 nm), with contents of 3%, 6% and 10% in relation to the mass of Portland cement. Besides these mixtures, a reference concrete was prepared without the addition of TiO2. In the hardened state, tests to determine the compressive strength and modulus of elasticity were carried out. Also, microstructural aspects of the samples were investigated by scanning electron microscopy and mercury intrusion porosimetry. In the fresh state, the influence of the addition of TiO2 on the concrete compaction and conduction calorimetry curves was evaluated. The results obtained indicated that, with the addition of TiO2, there was an increase in the compressive strength at 28 days and a reduction in the modulus of elasticity of the concretes. The calorimetry results indicated greater formation of C–S–H (calcium silicate hydrate)-type structures in the photocatalytic concretes. The porosimetry and SEM results showed a better distribution and refinement of the pores in these concretes.

Utilization of waste glass in translucent and photocatalytic concrete

This article addresses the development of a translucent and air purifying concrete containing waste glass. The concrete composition was optimized applying the modified Andreasen & Andersen model to obtain a densely packed system of granular ingredients. Both untreated (unwashed) and washed waste glass fractions were utilized in concrete. The fresh and hardened concrete properties were investigated. In order to ensure a durable material, the expansion due to the alkali-silica reaction was also analyzed. Subsequently, concrete tiles of different thicknesses were produced and their translucency was quantified. Additionally, two different types of TiO2 were utilized in concrete to analyze the glass aggregates effect on the photocatalytic degradation of air pollutants (NO and NO2). The obtained results indicate that the developed concrete has satisfactory mechanical properties, coupled with good durability, translucency and enhanced air purification properties.

Evaluation of Mechanical Behavior and Microstructural Characteristics of Photocatalytic Concretes to Be Used as Pavement Blocks

This paper reports the results obtained in a study on the effect of the addition of TiO2 nanoparticles on the mechanical properties and microstructural characteristics of photocatalytic concretes. In the hardened state, tests to determine the compressive strength and modulus of elasticity were carried out. Also, microstructural aspects of the samples were investigated. In the fresh state, the influence of the addition of TiO2 on the concrete compaction and conduction calorimetry curves was evaluated. The results obtained indicated a better mechanical and microstructural behavior of concrete with addition of TiO2.

Photocatalytic concretes — The interface between photocatalysis and cement chemistry

Concrete materials are ubiquitous in the developed world due to their versatility and cost-effectiveness as a construction material, but their great potential for increased functionality remains underdeveloped. As supports for photocatalysts, these structures offer viable solutions for the reduction of atmospheric pollutant concentrations, the source of which is often associated with urbanisation and the built infrastructure. This paper addresses (i) the photocatalytic mechanisms applicable to atmospheric depollution, (ii) the influence of doping, and (iii) the application of TiO2-based photocatalysts to concrete. Modifications to TiO2 will be discussed which can improve its activation in visible light and, in the treatment of NOx, improve catalytic selectivity towards nitrate rather than the more toxic NO2. The influence of the chemistry of cements on catalyst performance during both concrete placement and in service will also be addressed and some attention will be given to alternative strategies for introducing the photocatalyst to the concrete.

Новые высокоэффективные нанодобавки для фотокаталитических бетонов: синтез и исследование

Новые высокоэффективные нанодобавки для фотокаталитических бетонов: синтез и исследование

Recent Development of Nano Titanium Dioxide to Be Used in the Field of Building Materials

In recent years, the photocatalytic properties of nano TiO2 (nanotitanium dioxide) is one of today’s hottest issues of environmentally friendly materials, medical materials and building materials fields. In this paper, we present the latest research on nanotitanium dioxide to be used in the field of building materials. Based on the history of the photocatalytic properties of nanotitanium dioxide, the application of nanotitanium dioxide in photocatalytic concrete, photocatalytic ceramics, functional coatings and materials in the field of self-cleaning glass has been analyzed. Finally, further research will focus on nanotitanium dioxide used in the field of building materials.

Preparation of titanium dioxide nano particle modified photocatalytic self-cleaning concrete

The self-cleaning concrete is a potential approach to make the city cleaner by reducing the air pollutants. In this study, a photocatalytic concrete with ultra-smooth surface was fabricated with a new approach taking use of the nano granular nature of the main hydration product of cement i.e. Calcium Silicate Hydrates (C–S–H) and the photocatalysis properties of TiO2 nano particles. Results show that the surface of the fabricated concrete was covered by C–S–H and TiO2 nano particles around tens of nm; the surface roughness of the concrete was 3.5–11 nm; the surface of the photocatalytic ultra-smooth concrete can degrade methylene blue (MB) effectively. Due to its ultra-smooth surface and photocatalytic properties, the residue of contaminants will be washed away by the rain, this new type of concrete is promising to be utilized as a self-cleaning finishing material for the urban buildings.

도로구조물 적용을 위한 광촉매 콘크리트의 질소산화물(NOx) 제거효율 평가

도로구조물 적용을 위한 광촉매 콘크리트의 질소산화물(NOx) 제거효율 평가

Recent Photocatalytic Applications for Air Purification in Belgium

Photocatalytic concrete constitutes a promising technique to reduce a number of air contaminants such as NOx and VOC’s, especially at sites with a high level of pollution: highly trafficked canyon streets, road tunnels, the urban environment, etc. Ideally, the photocatalyst, titanium dioxide, is introduced in the top layer of the concrete pavement for best results. In addition, the combination of TiO2 with cement-based products offers some synergistic advantages, as the reaction products can be adsorbed at the surface and subsequently be washed away by rain. A first application has been studied by the Belgian Road Research Center (BRRC) on the side roads of a main entrance axis in Antwerp with the installation of 10.000 m² of photocatalytic concrete paving blocks. For now however, the translation of laboratory testing towards results in situ remains critical of demonstrating the effectiveness in large scale applications. Moreover, the durability of the air cleaning characteristic with time remains challenging for application in concrete roads. From this perspective, several new trial applications have been initiated in Belgium in recent years to assess the “real life” behavior, including a field site set up in the Leopold II tunnel of Brussels and the construction of new photocatalytic pavements on industrial zones in the cities of Wijnegem and Lier (province of Antwerp). This paper first gives a short overview of the photocatalytic principle applied in concrete, to continue with some main results of the laboratory research recognizing the important parameters that come into play. In addition, some of the methods and results, obtained for the existing application in Antwerp (2005) and during the implementation of the new realizations in Wijnegem and Lier (2010–2012) and in Brussels (2011–2013), will be presented.

Life-cycle cost analysis of highway noise barriers designed with photocatalytic cement

This study examines the environmental and economic feasibility of concrete noise barriers containing photocatalytic cement using a life-cycle cost analysis (LCCA). Photocatalytic concrete contains titanium dioxide (TiO2) which allows for the oxidation of air pollutants to occur on the surface of the building material. Design variables studied include the cementing material type (general use (GU) cement, ground granulated blast furnace slag (GGBFS) used as cement replacement, and photocatalytic (PCAT) cement), and the thickness of a photocatalytic concrete cover. The LCCA accounts for the CO2 and NOx generated during manufacturing and the NOx (NO, NO2) oxidised during the life of barriers containing photocatalytic concrete. A key outcome from this study revealed that at a 40-year service life, assuming a 6 mg/h/m2 NOx degradation rate, a barrier designed with 100%GU cement and a 25 mm photocatalytic concrete cover has an annual cost that is 7%, 30%, and 36% greater than the 100%GU, 35% and 50%GGBFS barriers without a photocatalytic cover, respectively. Results of this analysis also indicated that the application of a 25 mm photocatalytic concrete cover to concrete containing 35 and 50%GGBFS is more economically feasible than 100%GU concrete, irrespective of the service life and pollution degradation rate.

Application of Photocatalytic Concrete Paint and its Effect of Decomposing Vehicle Exhaust

With the widely research of Photocatalytic titanium dioxide, researchers have found another way of managing air quality. As an excellent photocatalyst material, nanometer titanium dioxide has begun to be used in road engineering in recent years. In this paper, at first, different content of titanium dioxide were dispersed evenly and separately in a kind of silane solvent to make the coating material with photocatalytic performance. The results show that nanometer titanium dioxide is able to decompose CO, HC, NO and CO2 after being dispersed in silane solvent. The results also show that a certain content oftitanium dioxide can be chosen after considering effect, workability and economic factors in practical application. Then the brushing method and the decomposition effect of the photocatalytic paint are discussed. The tests indicate that proper content of nanometer titanium dioxide with suitable brushing method can maximize catalytic efficiency. At last, in order to study the decomposition mechanism, using ion chromatography and chemical titration to analyze the decomposition products separately, the results prove that nanometer titanium dioxide can decompose NO, HC, CO and other harmful gases into nitrate and carbonate.

Mutual interactions between carbonation and titanium dioxide photoactivity in concrete

The use of building materials modified with photocatalytic components is constantly growing, due to an increased need for efficient purification strategies to improve air quality in industrial and urban areas. Yet, few works are available on the actual behavior of photocatalysts integrated in supporting materials, in this case concrete, and on the alteration of their properties in time. This work focuses on mechanical and durability aspects of TiO2-containing photocatalytic concrete by examining mutual influences between TiO2 and concrete components, and their evolution with the material aging. Experimental tests showed that concrete rheological properties decreased by adding TiO2; mechanical resistance also decreased slightly, in spite of the filler effect expected from the addition of a nanopowder. On the other hand, carbonation decreased the material photocatalytic efficiency compared to the freshly cast specimens: this was ascribed to variations of pore solution chemistry and possible shielding effects produced by calcium carbonate precipitation.

Photocatalytic roads: from lab tests to real scale applications

This paper gives an overview of our research on photocatalytic concrete, which exhibits air purifying properties. Under the action of sunlight, a catalyst present at the surface of the material is activated, enabling degradation of pollutants from the surroundings and transformation to less harmful products. It is a promising technique to reduce a number of air contaminants, especially at sites with a high level of pollution: highly trafficked canyon streets, road tunnels, etc. In addition, the combination with cement offers some synergistic advantages, as the reaction products can be adsorbed at the surface and subsequently washed away by rain. However, the great potential of this emerging technology is hampered by the lack of uniform testing methods at European level to evaluate the photocatalytic activity. Laboratory research is undertaken at BRRC to compare existing methods and draw up recommendations for future standards. Furthermore, translation of lab testing towards results in situ remains critical to demonstrate the effectiveness on larger scale. In this perspective, several trial applications have recently been initiated in Belgium to asses the “real life” behavior. The paper gives a short overview of the photocatalytic principle and the application in concrete, as well as some main results of the laboratory research recognizing the important parameters that come into play. In addition, the implementation efforts of some recent realizations in Belgium will be presented. Already some very promising results towards air purification have been obtained. Nevertheless, further validation, also with modeling, is necessary to extrapolate the findings and enable a judicial implementation of photocatalytic road materials across the globe.

Nitrogen Oxide Reduction and Nitrate Measurements on TiO2 Photocatalytic Pervious Concrete Pavement

Heterogeneous photocatalysis is considered one of the potential solutions for pollution remediation in which the natural decomposition process of harmful air pollutants is accelerated. This process make use of photocatalytic agents like nano titanium dioxide. Nano titanium dioxide (TiO_2) has been found to have photocatalytic properties in which under UV light can oxidize and remove VOCs and NO_x from the atmosphere. Therefore, the objective of this study is to evaluate the amount of nitrates released due to pervious photocatalytic concrete. To achieve this objective, samples were tested in the laboratory for photocatalytic Nitrogen Oxide (NO_x) reduction efficiency according to the Japanese Industrial Standard (JIS). After testing, samples were washed with deionized water to collect the nitrates deposited on the surface. The collected nitrate concentration was measured using colorimetric method (cadmium reduction). In addition, a parametric study was conducted to examine the performance of pervious photocatalytic concrete under different environmental conditions. Results showed that photocatalytic pervious concrete is capable of purifying ambient air from NO_x. In addition, a good agreement was obtained between the total amount of nitrogen compound eluted and the net amount of NOx removed under different mix design and environmental conditions. Results indicated that photocatalytic efficiency improved with the decrease in humidity, decrease in flow rate, and the increase in UV light intensity.

Quantification of Reduction of Nitrogen Oxides by Nitrate Accumulation on Titanium Dioxide Photocatalytic Concrete Pavement

Field trials of photocatalytic pavements were recently initiated and are being considered by many states (e.g., Virginia, Texas, New York, and Missouri). Results from this study are from the country's first air-purifying asphalt and concrete photocatalytic pavements on December 20, 2010. The test area was a pavement site located on the Louisiana State University campus in Baton Rouge. The objective of this study was validation of photocatalytic degradation of nitrogen oxides (NOx) at the test site by measuring nitrate salts (NO3) deposited on the pavement surface. With quantification of the nitrate levels produced in the field attributable to photocatalytic activity, measurements were correlated to laboratory test results of NOx reduction efficiency. A field sampling procedure of NO3 deposited on the pavement surface is presented. On the basis of the results of the experimental program, the proposed method to quantify photocatalytic efficiency through nitrate measurements was successful. There was definite evidence that photocatalytic degradation of NOx was taking place in the treated section. In addition, the photocatalytic process was active during the first 4 days followed by a slight decrease in degradation of NOx. Full regeneration of photo catalytic activity took place through a self-cleaning process during a rain event. Six months of traffic and in-service operating conditions had negligible effects on the efficiency of the photocatalytic coating. In addition, there was good agreement between nitric oxide removal efficiency measured in the field after one day of nitrate accumulation and in the laboratory at the same relative humidity.

Experimental study of the NO and NO 2 degradation by photocatalytically active concrete

The application of photocatalytic concrete containing TiO 2 in urban streets is a method to improve the air quality in highly polluted areas. By using this technology it is possible to degrade a wide range of air contaminants, like nitric oxide (NO) and nitrogen dioxide (NO 2), mainly emitted by automobiles. In the present paper, the photocatalytic degradation of NO and NO 2 is experimentally studied, and the atmospheric reactions involving nitrogen oxides and solar radiation are analyzed as well. In addition, the influence of different system parameters, such as inlet pollutant concentration, relative humidity, and irradiance is investigated in detail.

光触媒を利用した透水性インターロッキングブロックのNOx除去性能に及ぼす各種要因の影響

Nitrogen oxides in exhaust gases from automobiles have been causing so serious air pollution in urban areas that building materials with a NOx removal performance have been required. We have developed a photocatalytic concrete with an oxidative NOx removal performance by means of a photocatalytic activity of titanium dioxide. The photocatalytic concrete is used for paving blocks. We researched the influence of various factors on the NOx removal performance of the photocatalytic paving blocks. As a result, it turned out that the paving blocks had the performance by which NOx was removed from the ambient air on a roadside.